Juvenile-onset recurrent respiratory papillomatosis (JORRP) is a childhood disease characterized by growth of benign papilloma in the respiratory tract, most frequently on the vocal fold. Some children undergo over one hundred surgical procedures to remove recurrent papillomas. JORRP is caused by perinatal mother-to-child transmission of HPV types 6 and 11 which are also responsible for genital warts. The proposed population-based, retrospective, cohort study plans to analyze data in Danish National Registries to address two specific aims: (1) to estimate the relative risk of JORRP in offspring of mothers who have condyloma during pregnancy or at delivery and to identify additional risk factors for transmission of JORRP; and (2) to examine if the above risk is reduced by cesarean delivery of the at-risk infants. Pregnancies with the diagnoses of maternal condyloma will be identified in a search of over one million pregnancies in Denmark in the time period 1974-1993. It is estimated that about 3,000 such pregnancies will be identified. The incidence of JORRP in children from these pregnancies will be compared with that in children from non-exposed pregnancies. Factors that may influence the transmission of JORRP (virus type in condyloma, maternal age, parity, medical intervention and others) will be identified. It is anticipated that about 15 percent of the births will be by cesarean delivery. Maternal condyloma is not an indication for cesarean delivery in Denmark. Therefore, it will be possible to examine if cesarean delivery reduces the risk of JORRP in the offspring of condylomatous women. The results of this investigation may clarify questions in the biology of JORRP and also help to identify circumstances in which cesarean delivery would be appropriate to reduce the risk of JORRP.